*2.3. Investigation of Temperature Fields in the Cutting Wedge*

The semiartificial clamped microthermocouple method was used [82] to study the temperature fields in the cutting wedge of the tool. Composite plates of various tool materials were used, divided by the main intersection plane (cutting edge normal plane) into two parts, tightly (without a gap) compressed by pins before sharpening, excluding the possibility of their relative displacement to lay semiartificial microthermocouples. The articulating surfaces of each part of the plate were carefully lapped until a roughness *R*<sup>a</sup> of no more than 0.04 μm was achieved. The position of the interface plane corresponds to the cutting zone at the tool–chip interface section position, in which the temperatures caused by the contact interaction of the tool and the workpiece are maximum. A constantan wire with a diameter of 0.1 mm, insulated with spacers, was placed at a given point of the cutting zone at the tool–chip interface section along a groove in one of the parts of the composite plate. An uninsulated flattened end with a wire thickness of less than 10 μm was compressed between two ground surfaces of the composite plate portions. The wire contact area with the plate (thermocouple hot junction) was adjusted to a size of 0.15 mm × 0.15 mm. The studies were carried out on a ZMM-Sliven CU500/1000 screw-cutting lathe (ZMM, Nova Zagora, Bulgaria) when simulating the interrupted machining in longitudinal turning with a constant cut section of a workpiece made of 41CrS4 steel (HB 240), on which the grooves were previously milled. It provided the conditions for intermittent operation of the tool close to the milling process. The tests were carried out at a cutting speed *V* = 68 m/min, feed *f* = 0.15 mm/rev, depth *t* = 2.0 mm with a working stroke length of 90 mm, and an idle stroke of 45 mm.
